The objectives of the Fusion-Inhibitor Acquisition, Evaluation and Formulation Core are: 1) To acquire and characterize inhibitors of HIV-1 attachment, fusion and entry that are credible candidates for further evaluation as microbicides in the in vitro and macaque model experimental systems; 2) To facilitate the formulation of these inhibitors in a way that is suitable for their vaginal and rectal administration and evaluation as candidate microbicides in the macaque models. The Core Leader will be John P. Moore, Ph.D., the Core co-Leader will be Robert W. Doms, M.D. This Research Support Core will be located at the Weill Medical College of Cornell University with a sub-contract to Dr. Doms at the University of Pennsylvania. The principal function of the Core will be to act as a central resource to support the individual Research Projects. The Core will obtain, by collaboration or purchase, sufficient quantities of suitable fusion/entry inhibitors for use in all three Research Projects, thereby ensuring that a common set of reagents will be used throughout this Program Project. The Core will characterize these inhibitors, to determine their potency against a range of HIV-1 isolates in vitro, using well-established experimental systems based on primary lymphocytes and macrophages. This work will ensure that only bonafide, active reagents are used in each of the Research Projects. The Core will determine which combinations of inhibitors are most suitable for further evaluation in the in vitro model systems (Research Projects I and II) and, in particular, in the rhesus macaque model (Research Project III). The Core will organize and supply expertise in microbicide formulation, together with properly formulated inhibitors, to the PL of Research Project III to ensure that candidate microbicides are appropriately tested in the rhesus macaque vaginal and rectal transmission models.